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Server job assigning logic, submarine movement syncing, submarine collision improvements, spawnpoints in levels

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Regalis
2015-07-08 11:37:47 +03:00
parent 3af9b8183b
commit d56f7f3f77
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Farseer Physics Engine 3.5/Dynamics/Contacts/Contact.cs
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/*
* Farseer Physics Engine:
* Copyright (c) 2012 Ian Qvist
*
* Original source Box2D:
* Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
//#define USE_ACTIVE_CONTACT_SET
using System.Collections.Generic;
using System.Diagnostics;
using FarseerPhysics.Collision;
using FarseerPhysics.Collision.Shapes;
using FarseerPhysics.Common;
using Microsoft.Xna.Framework;
namespace FarseerPhysics.Dynamics.Contacts
{
/// <summary>
/// A contact edge is used to connect bodies and contacts together
/// in a contact graph where each body is a node and each contact
/// is an edge. A contact edge belongs to a doubly linked list
/// maintained in each attached body. Each contact has two contact
/// nodes, one for each attached body.
/// </summary>
public sealed class ContactEdge
{
/// <summary>
/// The contact
/// </summary>
public Contact Contact;
/// <summary>
/// The next contact edge in the body's contact list
/// </summary>
public ContactEdge Next;
/// <summary>
/// Provides quick access to the other body attached.
/// </summary>
public Body Other;
/// <summary>
/// The previous contact edge in the body's contact list
/// </summary>
public ContactEdge Prev;
}
/// <summary>
/// The class manages contact between two shapes. A contact exists for each overlapping
/// AABB in the broad-phase (except if filtered). Therefore a contact object may exist
/// that has no contact points.
/// </summary>
public class Contact
{
private ContactType _type;
private static EdgeShape _edge = new EdgeShape();
private static ContactType[,] _registers = new[,]
{
{
ContactType.Circle,
ContactType.EdgeAndCircle,
ContactType.PolygonAndCircle,
ContactType.ChainAndCircle,
},
{
ContactType.EdgeAndCircle,
ContactType.NotSupported,
// 1,1 is invalid (no ContactType.Edge)
ContactType.EdgeAndPolygon,
ContactType.NotSupported,
// 1,3 is invalid (no ContactType.EdgeAndLoop)
},
{
ContactType.PolygonAndCircle,
ContactType.EdgeAndPolygon,
ContactType.Polygon,
ContactType.ChainAndPolygon,
},
{
ContactType.ChainAndCircle,
ContactType.NotSupported,
// 3,1 is invalid (no ContactType.EdgeAndLoop)
ContactType.ChainAndPolygon,
ContactType.NotSupported,
// 3,3 is invalid (no ContactType.Loop)
},
};
// Nodes for connecting bodies.
internal ContactEdge _nodeA = new ContactEdge();
internal ContactEdge _nodeB = new ContactEdge();
internal int _toiCount;
internal float _toi;
public Fixture FixtureA;
public Fixture FixtureB;
public float Friction { get; set; }
public float Restitution { get; set; }
/// <summary>
/// Get the contact manifold. Do not modify the manifold unless you understand the
/// internals of Box2D.
/// </summary>
public Manifold Manifold;
/// Get or set the desired tangent speed for a conveyor belt behavior. In meters per second.
public float TangentSpeed { get; set; }
/// Enable/disable this contact. This can be used inside the pre-solve
/// contact listener. The contact is only disabled for the current
/// time step (or sub-step in continuous collisions).
/// NOTE: If you are setting Enabled to a constant true or false,
/// use the explicit Enable() or Disable() functions instead to
/// save the CPU from doing a branch operation.
public bool Enabled { get; set; }
/// <summary>
/// Get the child primitive index for fixture A.
/// </summary>
/// <value>The child index A.</value>
public int ChildIndexA { get; internal set; }
/// <summary>
/// Get the child primitive index for fixture B.
/// </summary>
/// <value>The child index B.</value>
public int ChildIndexB { get; internal set; }
/// <summary>
/// Determines whether this contact is touching.
/// </summary>
/// <returns>
/// <c>true</c> if this instance is touching; otherwise, <c>false</c>.
/// </returns>
public bool IsTouching { get; set; }
internal bool IslandFlag { get; set; }
internal bool TOIFlag { get; set; }
internal bool FilterFlag { get; set; }
public void ResetRestitution()
{
Restitution = Settings.MixRestitution(FixtureA.Restitution, FixtureB.Restitution);
}
public void ResetFriction()
{
Friction = Settings.MixFriction(FixtureA.Friction, FixtureB.Friction);
}
private Contact(Fixture fA, int indexA, Fixture fB, int indexB)
{
Reset(fA, indexA, fB, indexB);
}
/// <summary>
/// Gets the world manifold.
/// </summary>
public void GetWorldManifold(out Vector2 normal, out FixedArray2<Vector2> points)
{
Body bodyA = FixtureA.Body;
Body bodyB = FixtureB.Body;
Shape shapeA = FixtureA.Shape;
Shape shapeB = FixtureB.Shape;
ContactSolver.WorldManifold.Initialize(ref Manifold, ref bodyA._xf, shapeA.Radius, ref bodyB._xf, shapeB.Radius, out normal, out points);
}
private void Reset(Fixture fA, int indexA, Fixture fB, int indexB)
{
Enabled = true;
IsTouching = false;
IslandFlag = false;
FilterFlag = false;
TOIFlag = false;
FixtureA = fA;
FixtureB = fB;
ChildIndexA = indexA;
ChildIndexB = indexB;
Manifold.PointCount = 0;
_nodeA.Contact = null;
_nodeA.Prev = null;
_nodeA.Next = null;
_nodeA.Other = null;
_nodeB.Contact = null;
_nodeB.Prev = null;
_nodeB.Next = null;
_nodeB.Other = null;
_toiCount = 0;
//FPE: We only set the friction and restitution if we are not destroying the contact
if (FixtureA != null && FixtureB != null)
{
Friction = Settings.MixFriction(FixtureA.Friction, FixtureB.Friction);
Restitution = Settings.MixRestitution(FixtureA.Restitution, FixtureB.Restitution);
}
TangentSpeed = 0;
}
/// <summary>
/// Update the contact manifold and touching status.
/// Note: do not assume the fixture AABBs are overlapping or are valid.
/// </summary>
/// <param name="contactManager">The contact manager.</param>
internal void Update(ContactManager contactManager)
{
Body bodyA = FixtureA.Body;
Body bodyB = FixtureB.Body;
if (FixtureA == null || FixtureB == null)
return;
Manifold oldManifold = Manifold;
// Re-enable this contact.
Enabled = true;
bool touching;
bool wasTouching = IsTouching;
bool sensor = FixtureA.IsSensor || FixtureB.IsSensor;
// Is this contact a sensor?
if (sensor)
{
Shape shapeA = FixtureA.Shape;
Shape shapeB = FixtureB.Shape;
touching = Collision.Collision.TestOverlap(shapeA, ChildIndexA, shapeB, ChildIndexB, ref bodyA._xf, ref bodyB._xf);
// Sensors don't generate manifolds.
Manifold.PointCount = 0;
}
else
{
Evaluate(ref Manifold, ref bodyA._xf, ref bodyB._xf);
touching = Manifold.PointCount > 0;
// Match old contact ids to new contact ids and copy the
// stored impulses to warm start the solver.
for (int i = 0; i < Manifold.PointCount; ++i)
{
ManifoldPoint mp2 = Manifold.Points[i];
mp2.NormalImpulse = 0.0f;
mp2.TangentImpulse = 0.0f;
ContactID id2 = mp2.Id;
for (int j = 0; j < oldManifold.PointCount; ++j)
{
ManifoldPoint mp1 = oldManifold.Points[j];
if (mp1.Id.Key == id2.Key)
{
mp2.NormalImpulse = mp1.NormalImpulse;
mp2.TangentImpulse = mp1.TangentImpulse;
break;
}
}
Manifold.Points[i] = mp2;
}
if (touching != wasTouching)
{
bodyA.Awake = true;
bodyB.Awake = true;
}
}
IsTouching = touching;
if (wasTouching == false)
{
if (touching)
{
if (Settings.AllCollisionCallbacksAgree)
{
bool enabledA = true, enabledB = true;
// Report the collision to both participants. Track which ones returned true so we can
// later call OnSeparation if the contact is disabled for a different reason.
if (FixtureA.OnCollision != null)
foreach (OnCollisionEventHandler handler in FixtureA.OnCollision.GetInvocationList())
enabledA = handler(FixtureA, FixtureB, this) && enabledA;
// Reverse the order of the reported fixtures. The first fixture is always the one that the
// user subscribed to.
if (FixtureB.OnCollision != null)
foreach (OnCollisionEventHandler handler in FixtureB.OnCollision.GetInvocationList())
enabledB = handler(FixtureB, FixtureA, this) && enabledB;
Enabled = enabledA && enabledB;
// BeginContact can also return false and disable the contact
if (enabledA && enabledB && contactManager.BeginContact != null)
Enabled = contactManager.BeginContact(this);
}
else
{
//Report the collision to both participants:
if (FixtureA.OnCollision != null)
foreach (OnCollisionEventHandler handler in FixtureA.OnCollision.GetInvocationList())
Enabled = handler(FixtureA, FixtureB, this);
//Reverse the order of the reported fixtures. The first fixture is always the one that the
//user subscribed to.
if (FixtureB.OnCollision != null)
foreach (OnCollisionEventHandler handler in FixtureB.OnCollision.GetInvocationList())
Enabled = handler(FixtureB, FixtureA, this);
//BeginContact can also return false and disable the contact
if (contactManager.BeginContact != null)
Enabled = contactManager.BeginContact(this);
}
// If the user disabled the contact (needed to exclude it in TOI solver) at any point by
// any of the callbacks, we need to mark it as not touching and call any separation
// callbacks for fixtures that didn't explicitly disable the collision.
if (!Enabled)
IsTouching = false;
}
}
else
{
if (touching == false)
{
//Report the separation to both participants:
if (FixtureA != null && FixtureA.OnSeparation != null)
FixtureA.OnSeparation(FixtureA, FixtureB);
//Reverse the order of the reported fixtures. The first fixture is always the one that the
//user subscribed to.
if (FixtureB != null && FixtureB.OnSeparation != null)
FixtureB.OnSeparation(FixtureB, FixtureA);
if (contactManager.EndContact != null)
contactManager.EndContact(this);
}
}
if (sensor)
return;
if (contactManager.PreSolve != null)
contactManager.PreSolve(this, ref oldManifold);
}
/// <summary>
/// Evaluate this contact with your own manifold and transforms.
/// </summary>
/// <param name="manifold">The manifold.</param>
/// <param name="transformA">The first transform.</param>
/// <param name="transformB">The second transform.</param>
private void Evaluate(ref Manifold manifold, ref Transform transformA, ref Transform transformB)
{
switch (_type)
{
case ContactType.Polygon:
Collision.Collision.CollidePolygons(ref manifold, (PolygonShape)FixtureA.Shape, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
break;
case ContactType.PolygonAndCircle:
Collision.Collision.CollidePolygonAndCircle(ref manifold, (PolygonShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
break;
case ContactType.EdgeAndCircle:
Collision.Collision.CollideEdgeAndCircle(ref manifold, (EdgeShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
break;
case ContactType.EdgeAndPolygon:
Collision.Collision.CollideEdgeAndPolygon(ref manifold, (EdgeShape)FixtureA.Shape, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
break;
case ContactType.ChainAndCircle:
ChainShape chain = (ChainShape)FixtureA.Shape;
chain.GetChildEdge(_edge, ChildIndexA);
Collision.Collision.CollideEdgeAndCircle(ref manifold, _edge, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
break;
case ContactType.ChainAndPolygon:
ChainShape loop2 = (ChainShape)FixtureA.Shape;
loop2.GetChildEdge(_edge, ChildIndexA);
Collision.Collision.CollideEdgeAndPolygon(ref manifold, _edge, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
break;
case ContactType.Circle:
Collision.Collision.CollideCircles(ref manifold, (CircleShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
break;
}
}
internal static Contact Create(Fixture fixtureA, int indexA, Fixture fixtureB, int indexB)
{
ShapeType type1 = fixtureA.Shape.ShapeType;
ShapeType type2 = fixtureB.Shape.ShapeType;
Debug.Assert(ShapeType.Unknown < type1 && type1 < ShapeType.TypeCount);
Debug.Assert(ShapeType.Unknown < type2 && type2 < ShapeType.TypeCount);
Contact c;
Queue<Contact> pool = fixtureA.Body._world._contactPool;
if (pool.Count > 0)
{
c = pool.Dequeue();
if ((type1 >= type2 || (type1 == ShapeType.Edge && type2 == ShapeType.Polygon)) && !(type2 == ShapeType.Edge && type1 == ShapeType.Polygon))
{
c.Reset(fixtureA, indexA, fixtureB, indexB);
}
else
{
c.Reset(fixtureB, indexB, fixtureA, indexA);
}
}
else
{
// Edge+Polygon is non-symetrical due to the way Erin handles collision type registration.
if ((type1 >= type2 || (type1 == ShapeType.Edge && type2 == ShapeType.Polygon)) && !(type2 == ShapeType.Edge && type1 == ShapeType.Polygon))
{
c = new Contact(fixtureA, indexA, fixtureB, indexB);
}
else
{
c = new Contact(fixtureB, indexB, fixtureA, indexA);
}
}
c._type = _registers[(int)type1, (int)type2];
return c;
}
internal void Destroy()
{
#if USE_ACTIVE_CONTACT_SET
FixtureA.Body.World.ContactManager.RemoveActiveContact(this);
#endif
FixtureA.Body._world._contactPool.Enqueue(this);
if (Manifold.PointCount > 0 && FixtureA.IsSensor == false && FixtureB.IsSensor == false)
{
FixtureA.Body.Awake = true;
FixtureB.Body.Awake = true;
}
Reset(null, 0, null, 0);
}
#region Nested type: ContactType
private enum ContactType
{
NotSupported,
Polygon,
PolygonAndCircle,
Circle,
EdgeAndPolygon,
EdgeAndCircle,
ChainAndPolygon,
ChainAndCircle,
}
#endregion
}
}
Farseer Physics Engine 3.5/Dynamics/Contacts/ContactSolver.cs
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/*
* Farseer Physics Engine:
* Copyright (c) 2012 Ian Qvist
*
* Original source Box2D:
* Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
using System;
using System.Diagnostics;
using FarseerPhysics.Collision;
using FarseerPhysics.Collision.Shapes;
using FarseerPhysics.Common;
using Microsoft.Xna.Framework;
namespace FarseerPhysics.Dynamics.Contacts
{
public sealed class ContactPositionConstraint
{
public Vector2[] localPoints = new Vector2[Settings.MaxManifoldPoints];
public Vector2 localNormal;
public Vector2 localPoint;
public int indexA;
public int indexB;
public float invMassA, invMassB;
public Vector2 localCenterA, localCenterB;
public float invIA, invIB;
public ManifoldType type;
public float radiusA, radiusB;
public int pointCount;
}
public sealed class VelocityConstraintPoint
{
public Vector2 rA;
public Vector2 rB;
public float normalImpulse;
public float tangentImpulse;
public float normalMass;
public float tangentMass;
public float velocityBias;
}
public sealed class ContactVelocityConstraint
{
public VelocityConstraintPoint[] points = new VelocityConstraintPoint[Settings.MaxManifoldPoints];
public Vector2 normal;
public Mat22 normalMass;
public Mat22 K;
public int indexA;
public int indexB;
public float invMassA, invMassB;
public float invIA, invIB;
public float friction;
public float restitution;
public float tangentSpeed;
public int pointCount;
public int contactIndex;
public ContactVelocityConstraint()
{
for (int i = 0; i < Settings.MaxManifoldPoints; i++)
{
points[i] = new VelocityConstraintPoint();
}
}
}
public class ContactSolver
{
public TimeStep _step;
public Position[] _positions;
public Velocity[] _velocities;
public ContactPositionConstraint[] _positionConstraints;
public ContactVelocityConstraint[] _velocityConstraints;
public Contact[] _contacts;
public int _count;
public void Reset(TimeStep step, int count, Contact[] contacts, Position[] positions, Velocity[] velocities, bool warmstarting = Settings.EnableWarmstarting)
{
_step = step;
_count = count;
_positions = positions;
_velocities = velocities;
_contacts = contacts;
// grow the array
if (_velocityConstraints == null || _velocityConstraints.Length < count)
{
_velocityConstraints = new ContactVelocityConstraint[count * 2];
_positionConstraints = new ContactPositionConstraint[count * 2];
for (int i = 0; i < _velocityConstraints.Length; i++)
{
_velocityConstraints[i] = new ContactVelocityConstraint();
}
for (int i = 0; i < _positionConstraints.Length; i++)
{
_positionConstraints[i] = new ContactPositionConstraint();
}
}
// Initialize position independent portions of the constraints.
for (int i = 0; i < _count; ++i)
{
Contact contact = contacts[i];
Fixture fixtureA = contact.FixtureA;
Fixture fixtureB = contact.FixtureB;
Shape shapeA = fixtureA.Shape;
Shape shapeB = fixtureB.Shape;
float radiusA = shapeA.Radius;
float radiusB = shapeB.Radius;
Body bodyA = fixtureA.Body;
Body bodyB = fixtureB.Body;
Manifold manifold = contact.Manifold;
int pointCount = manifold.PointCount;
Debug.Assert(pointCount > 0);
ContactVelocityConstraint vc = _velocityConstraints[i];
vc.friction = contact.Friction;
vc.restitution = contact.Restitution;
vc.tangentSpeed = contact.TangentSpeed;
vc.indexA = bodyA.IslandIndex;
vc.indexB = bodyB.IslandIndex;
vc.invMassA = bodyA._invMass;
vc.invMassB = bodyB._invMass;
vc.invIA = bodyA._invI;
vc.invIB = bodyB._invI;
vc.contactIndex = i;
vc.pointCount = pointCount;
vc.K.SetZero();
vc.normalMass.SetZero();
ContactPositionConstraint pc = _positionConstraints[i];
pc.indexA = bodyA.IslandIndex;
pc.indexB = bodyB.IslandIndex;
pc.invMassA = bodyA._invMass;
pc.invMassB = bodyB._invMass;
pc.localCenterA = bodyA._sweep.LocalCenter;
pc.localCenterB = bodyB._sweep.LocalCenter;
pc.invIA = bodyA._invI;
pc.invIB = bodyB._invI;
pc.localNormal = manifold.LocalNormal;
pc.localPoint = manifold.LocalPoint;
pc.pointCount = pointCount;
pc.radiusA = radiusA;
pc.radiusB = radiusB;
pc.type = manifold.Type;
for (int j = 0; j < pointCount; ++j)
{
ManifoldPoint cp = manifold.Points[j];
VelocityConstraintPoint vcp = vc.points[j];
if (Settings.EnableWarmstarting)
{
vcp.normalImpulse = _step.dtRatio * cp.NormalImpulse;
vcp.tangentImpulse = _step.dtRatio * cp.TangentImpulse;
}
else
{
vcp.normalImpulse = 0.0f;
vcp.tangentImpulse = 0.0f;
}
vcp.rA = Vector2.Zero;
vcp.rB = Vector2.Zero;
vcp.normalMass = 0.0f;
vcp.tangentMass = 0.0f;
vcp.velocityBias = 0.0f;
pc.localPoints[j] = cp.LocalPoint;
}
}
}
public void InitializeVelocityConstraints()
{
for (int i = 0; i < _count; ++i)
{
ContactVelocityConstraint vc = _velocityConstraints[i];
ContactPositionConstraint pc = _positionConstraints[i];
float radiusA = pc.radiusA;
float radiusB = pc.radiusB;
Manifold manifold = _contacts[vc.contactIndex].Manifold;
int indexA = vc.indexA;
int indexB = vc.indexB;
float mA = vc.invMassA;
float mB = vc.invMassB;
float iA = vc.invIA;
float iB = vc.invIB;
Vector2 localCenterA = pc.localCenterA;
Vector2 localCenterB = pc.localCenterB;
Vector2 cA = _positions[indexA].c;
float aA = _positions[indexA].a;
Vector2 vA = _velocities[indexA].v;
float wA = _velocities[indexA].w;
Vector2 cB = _positions[indexB].c;
float aB = _positions[indexB].a;
Vector2 vB = _velocities[indexB].v;
float wB = _velocities[indexB].w;
Debug.Assert(manifold.PointCount > 0);
Transform xfA = new Transform();
Transform xfB = new Transform();
xfA.q.Set(aA);
xfB.q.Set(aB);
xfA.p = cA - MathUtils.Mul(xfA.q, localCenterA);
xfB.p = cB - MathUtils.Mul(xfB.q, localCenterB);
Vector2 normal;
FixedArray2<Vector2> points;
WorldManifold.Initialize(ref manifold, ref xfA, radiusA, ref xfB, radiusB, out normal, out points);
vc.normal = normal;
int pointCount = vc.pointCount;
for (int j = 0; j < pointCount; ++j)
{
VelocityConstraintPoint vcp = vc.points[j];
vcp.rA = points[j] - cA;
vcp.rB = points[j] - cB;
float rnA = MathUtils.Cross(vcp.rA, vc.normal);
float rnB = MathUtils.Cross(vcp.rB, vc.normal);
float kNormal = mA + mB + iA * rnA * rnA + iB * rnB * rnB;
vcp.normalMass = kNormal > 0.0f ? 1.0f / kNormal : 0.0f;
Vector2 tangent = MathUtils.Cross(vc.normal, 1.0f);
float rtA = MathUtils.Cross(vcp.rA, tangent);
float rtB = MathUtils.Cross(vcp.rB, tangent);
float kTangent = mA + mB + iA * rtA * rtA + iB * rtB * rtB;
vcp.tangentMass = kTangent > 0.0f ? 1.0f / kTangent : 0.0f;
// Setup a velocity bias for restitution.
vcp.velocityBias = 0.0f;
float vRel = Vector2.Dot(vc.normal, vB + MathUtils.Cross(wB, vcp.rB) - vA - MathUtils.Cross(wA, vcp.rA));
if (vRel < -Settings.VelocityThreshold)
{
vcp.velocityBias = -vc.restitution * vRel;
}
}
// If we have two points, then prepare the block solver.
if (vc.pointCount == 2)
{
VelocityConstraintPoint vcp1 = vc.points[0];
VelocityConstraintPoint vcp2 = vc.points[1];
float rn1A = MathUtils.Cross(vcp1.rA, vc.normal);
float rn1B = MathUtils.Cross(vcp1.rB, vc.normal);
float rn2A = MathUtils.Cross(vcp2.rA, vc.normal);
float rn2B = MathUtils.Cross(vcp2.rB, vc.normal);
float k11 = mA + mB + iA * rn1A * rn1A + iB * rn1B * rn1B;
float k22 = mA + mB + iA * rn2A * rn2A + iB * rn2B * rn2B;
float k12 = mA + mB + iA * rn1A * rn2A + iB * rn1B * rn2B;
// Ensure a reasonable condition number.
const float k_maxConditionNumber = 1000.0f;
if (k11 * k11 < k_maxConditionNumber * (k11 * k22 - k12 * k12))
{
// K is safe to invert.
vc.K.ex = new Vector2(k11, k12);
vc.K.ey = new Vector2(k12, k22);
vc.normalMass = vc.K.Inverse;
}
else
{
// The constraints are redundant, just use one.
// TODO_ERIN use deepest?
vc.pointCount = 1;
}
}
}
}
public void WarmStart()
{
// Warm start.
for (int i = 0; i < _count; ++i)
{
ContactVelocityConstraint vc = _velocityConstraints[i];
int indexA = vc.indexA;
int indexB = vc.indexB;
float mA = vc.invMassA;
float iA = vc.invIA;
float mB = vc.invMassB;
float iB = vc.invIB;
int pointCount = vc.pointCount;
Vector2 vA = _velocities[indexA].v;
float wA = _velocities[indexA].w;
Vector2 vB = _velocities[indexB].v;
float wB = _velocities[indexB].w;
Vector2 normal = vc.normal;
Vector2 tangent = MathUtils.Cross(normal, 1.0f);
for (int j = 0; j < pointCount; ++j)
{
VelocityConstraintPoint vcp = vc.points[j];
Vector2 P = vcp.normalImpulse * normal + vcp.tangentImpulse * tangent;
wA -= iA * MathUtils.Cross(vcp.rA, P);
vA -= mA * P;
wB += iB * MathUtils.Cross(vcp.rB, P);
vB += mB * P;
}
_velocities[indexA].v = vA;
_velocities[indexA].w = wA;
_velocities[indexB].v = vB;
_velocities[indexB].w = wB;
}
}
public void SolveVelocityConstraints()
{
for (int i = 0; i < _count; ++i)
{
ContactVelocityConstraint vc = _velocityConstraints[i];
int indexA = vc.indexA;
int indexB = vc.indexB;
float mA = vc.invMassA;
float iA = vc.invIA;
float mB = vc.invMassB;
float iB = vc.invIB;
int pointCount = vc.pointCount;
Vector2 vA = _velocities[indexA].v;
float wA = _velocities[indexA].w;
Vector2 vB = _velocities[indexB].v;
float wB = _velocities[indexB].w;
Vector2 normal = vc.normal;
Vector2 tangent = MathUtils.Cross(normal, 1.0f);
float friction = vc.friction;
Debug.Assert(pointCount == 1 || pointCount == 2);
// Solve tangent constraints first because non-penetration is more important
// than friction.
for (int j = 0; j < pointCount; ++j)
{
VelocityConstraintPoint vcp = vc.points[j];
// Relative velocity at contact
Vector2 dv = vB + MathUtils.Cross(wB, vcp.rB) - vA - MathUtils.Cross(wA, vcp.rA);
// Compute tangent force
float vt = Vector2.Dot(dv, tangent) - vc.tangentSpeed;
float lambda = vcp.tangentMass * (-vt);
// b2Clamp the accumulated force
float maxFriction = friction * vcp.normalImpulse;
float newImpulse = MathUtils.Clamp(vcp.tangentImpulse + lambda, -maxFriction, maxFriction);
lambda = newImpulse - vcp.tangentImpulse;
vcp.tangentImpulse = newImpulse;
// Apply contact impulse
Vector2 P = lambda * tangent;
vA -= mA * P;
wA -= iA * MathUtils.Cross(vcp.rA, P);
vB += mB * P;
wB += iB * MathUtils.Cross(vcp.rB, P);
}
// Solve normal constraints
if (vc.pointCount == 1)
{
VelocityConstraintPoint vcp = vc.points[0];
// Relative velocity at contact
Vector2 dv = vB + MathUtils.Cross(wB, vcp.rB) - vA - MathUtils.Cross(wA, vcp.rA);
// Compute normal impulse
float vn = Vector2.Dot(dv, normal);
float lambda = -vcp.normalMass * (vn - vcp.velocityBias);
// b2Clamp the accumulated impulse
float newImpulse = Math.Max(vcp.normalImpulse + lambda, 0.0f);
lambda = newImpulse - vcp.normalImpulse;
vcp.normalImpulse = newImpulse;
// Apply contact impulse
Vector2 P = lambda * normal;
vA -= mA * P;
wA -= iA * MathUtils.Cross(vcp.rA, P);
vB += mB * P;
wB += iB * MathUtils.Cross(vcp.rB, P);
}
else
{
// Block solver developed in collaboration with Dirk Gregorius (back in 01/07 on Box2D_Lite).
// Build the mini LCP for this contact patch
//
// vn = A * x + b, vn >= 0, , vn >= 0, x >= 0 and vn_i * x_i = 0 with i = 1..2
//
// A = J * W * JT and J = ( -n, -r1 x n, n, r2 x n )
// b = vn0 - velocityBias
//
// The system is solved using the "Total enumeration method" (s. Murty). The complementary constraint vn_i * x_i
// implies that we must have in any solution either vn_i = 0 or x_i = 0. So for the 2D contact problem the cases
// vn1 = 0 and vn2 = 0, x1 = 0 and x2 = 0, x1 = 0 and vn2 = 0, x2 = 0 and vn1 = 0 need to be tested. The first valid
// solution that satisfies the problem is chosen.
//
// In order to account of the accumulated impulse 'a' (because of the iterative nature of the solver which only requires
// that the accumulated impulse is clamped and not the incremental impulse) we change the impulse variable (x_i).
//
// Substitute:
//
// x = a + d
//
// a := old total impulse
// x := new total impulse
// d := incremental impulse
//
// For the current iteration we extend the formula for the incremental impulse
// to compute the new total impulse:
//
// vn = A * d + b
// = A * (x - a) + b
// = A * x + b - A * a
// = A * x + b'
// b' = b - A * a;
VelocityConstraintPoint cp1 = vc.points[0];
VelocityConstraintPoint cp2 = vc.points[1];
Vector2 a = new Vector2(cp1.normalImpulse, cp2.normalImpulse);
Debug.Assert(a.X >= 0.0f && a.Y >= 0.0f);
// Relative velocity at contact
Vector2 dv1 = vB + MathUtils.Cross(wB, cp1.rB) - vA - MathUtils.Cross(wA, cp1.rA);
Vector2 dv2 = vB + MathUtils.Cross(wB, cp2.rB) - vA - MathUtils.Cross(wA, cp2.rA);
// Compute normal velocity
float vn1 = Vector2.Dot(dv1, normal);
float vn2 = Vector2.Dot(dv2, normal);
Vector2 b = new Vector2();
b.X = vn1 - cp1.velocityBias;
b.Y = vn2 - cp2.velocityBias;
// Compute b'
b -= MathUtils.Mul(ref vc.K, a);
const float k_errorTol = 1e-3f;
//B2_NOT_USED(k_errorTol);
for (; ; )
{
//
// Case 1: vn = 0
//
// 0 = A * x + b'
//
// Solve for x:
//
// x = - inv(A) * b'
//
Vector2 x = -MathUtils.Mul(ref vc.normalMass, b);
if (x.X >= 0.0f && x.Y >= 0.0f)
{
// Get the incremental impulse
Vector2 d = x - a;
// Apply incremental impulse
Vector2 P1 = d.X * normal;
Vector2 P2 = d.Y * normal;
vA -= mA * (P1 + P2);
wA -= iA * (MathUtils.Cross(cp1.rA, P1) + MathUtils.Cross(cp2.rA, P2));
vB += mB * (P1 + P2);
wB += iB * (MathUtils.Cross(cp1.rB, P1) + MathUtils.Cross(cp2.rB, P2));
// Accumulate
cp1.normalImpulse = x.X;
cp2.normalImpulse = x.Y;
#if B2_DEBUG_SOLVER
// Postconditions
dv1 = vB + MathUtils.Cross(wB, cp1.rB) - vA - MathUtils.Cross(wA, cp1.rA);
dv2 = vB + MathUtils.Cross(wB, cp2.rB) - vA - MathUtils.Cross(wA, cp2.rA);
// Compute normal velocity
vn1 = Vector2.Dot(dv1, normal);
vn2 = Vector2.Dot(dv2, normal);
b2Assert(b2Abs(vn1 - cp1.velocityBias) < k_errorTol);
b2Assert(b2Abs(vn2 - cp2.velocityBias) < k_errorTol);
#endif
break;
}
//
// Case 2: vn1 = 0 and x2 = 0
//
// 0 = a11 * x1 + a12 * 0 + b1'
// vn2 = a21 * x1 + a22 * 0 + b2'
//
x.X = -cp1.normalMass * b.X;
x.Y = 0.0f;
vn1 = 0.0f;
vn2 = vc.K.ex.Y * x.X + b.Y;
if (x.X >= 0.0f && vn2 >= 0.0f)
{
// Get the incremental impulse
Vector2 d = x - a;
// Apply incremental impulse
Vector2 P1 = d.X * normal;
Vector2 P2 = d.Y * normal;
vA -= mA * (P1 + P2);
wA -= iA * (MathUtils.Cross(cp1.rA, P1) + MathUtils.Cross(cp2.rA, P2));
vB += mB * (P1 + P2);
wB += iB * (MathUtils.Cross(cp1.rB, P1) + MathUtils.Cross(cp2.rB, P2));
// Accumulate
cp1.normalImpulse = x.X;
cp2.normalImpulse = x.Y;
#if B2_DEBUG_SOLVER
// Postconditions
dv1 = vB + MathUtils.Cross(wB, cp1.rB) - vA - MathUtils.Cross(wA, cp1.rA);
// Compute normal velocity
vn1 = Vector2.Dot(dv1, normal);
b2Assert(b2Abs(vn1 - cp1.velocityBias) < k_errorTol);
#endif
break;
}
//
// Case 3: vn2 = 0 and x1 = 0
//
// vn1 = a11 * 0 + a12 * x2 + b1'
// 0 = a21 * 0 + a22 * x2 + b2'
//
x.X = 0.0f;
x.Y = -cp2.normalMass * b.Y;
vn1 = vc.K.ey.X * x.Y + b.X;
vn2 = 0.0f;
if (x.Y >= 0.0f && vn1 >= 0.0f)
{
// Resubstitute for the incremental impulse
Vector2 d = x - a;
// Apply incremental impulse
Vector2 P1 = d.X * normal;
Vector2 P2 = d.Y * normal;
vA -= mA * (P1 + P2);
wA -= iA * (MathUtils.Cross(cp1.rA, P1) + MathUtils.Cross(cp2.rA, P2));
vB += mB * (P1 + P2);
wB += iB * (MathUtils.Cross(cp1.rB, P1) + MathUtils.Cross(cp2.rB, P2));
// Accumulate
cp1.normalImpulse = x.X;
cp2.normalImpulse = x.Y;
#if B2_DEBUG_SOLVER
// Postconditions
dv2 = vB + MathUtils.Cross(wB, cp2.rB) - vA - MathUtils.Cross(wA, cp2.rA);
// Compute normal velocity
vn2 = Vector2.Dot(dv2, normal);
b2Assert(b2Abs(vn2 - cp2.velocityBias) < k_errorTol);
#endif
break;
}
//
// Case 4: x1 = 0 and x2 = 0
//
// vn1 = b1
// vn2 = b2;
x.X = 0.0f;
x.Y = 0.0f;
vn1 = b.X;
vn2 = b.Y;
if (vn1 >= 0.0f && vn2 >= 0.0f)
{
// Resubstitute for the incremental impulse
Vector2 d = x - a;
// Apply incremental impulse
Vector2 P1 = d.X * normal;
Vector2 P2 = d.Y * normal;
vA -= mA * (P1 + P2);
wA -= iA * (MathUtils.Cross(cp1.rA, P1) + MathUtils.Cross(cp2.rA, P2));
vB += mB * (P1 + P2);
wB += iB * (MathUtils.Cross(cp1.rB, P1) + MathUtils.Cross(cp2.rB, P2));
// Accumulate
cp1.normalImpulse = x.X;
cp2.normalImpulse = x.Y;
break;
}
// No solution, give up. This is hit sometimes, but it doesn't seem to matter.
break;
}
}
_velocities[indexA].v = vA;
_velocities[indexA].w = wA;
_velocities[indexB].v = vB;
_velocities[indexB].w = wB;
}
}
public void StoreImpulses()
{
for (int i = 0; i < _count; ++i)
{
ContactVelocityConstraint vc = _velocityConstraints[i];
Manifold manifold = _contacts[vc.contactIndex].Manifold;
for (int j = 0; j < vc.pointCount; ++j)
{
ManifoldPoint point = manifold.Points[j];
point.NormalImpulse = vc.points[j].normalImpulse;
point.TangentImpulse = vc.points[j].tangentImpulse;
manifold.Points[j] = point;
}
_contacts[vc.contactIndex].Manifold = manifold;
}
}
public bool SolvePositionConstraints()
{
float minSeparation = 0.0f;
for (int i = 0; i < _count; ++i)
{
ContactPositionConstraint pc = _positionConstraints[i];
int indexA = pc.indexA;
int indexB = pc.indexB;
Vector2 localCenterA = pc.localCenterA;
float mA = pc.invMassA;
float iA = pc.invIA;
Vector2 localCenterB = pc.localCenterB;
float mB = pc.invMassB;
float iB = pc.invIB;
int pointCount = pc.pointCount;
Vector2 cA = _positions[indexA].c;
float aA = _positions[indexA].a;
Vector2 cB = _positions[indexB].c;
float aB = _positions[indexB].a;
// Solve normal constraints
for (int j = 0; j < pointCount; ++j)
{
Transform xfA = new Transform();
Transform xfB = new Transform();
xfA.q.Set(aA);
xfB.q.Set(aB);
xfA.p = cA - MathUtils.Mul(xfA.q, localCenterA);
xfB.p = cB - MathUtils.Mul(xfB.q, localCenterB);
Vector2 normal;
Vector2 point;
float separation;
PositionSolverManifold.Initialize(pc, xfA, xfB, j, out normal, out point, out separation);
Vector2 rA = point - cA;
Vector2 rB = point - cB;
// Track max constraint error.
minSeparation = Math.Min(minSeparation, separation);
// Prevent large corrections and allow slop.
float C = MathUtils.Clamp(Settings.Baumgarte * (separation + Settings.LinearSlop), -Settings.MaxLinearCorrection, 0.0f);
// Compute the effective mass.
float rnA = MathUtils.Cross(rA, normal);
float rnB = MathUtils.Cross(rB, normal);
float K = mA + mB + iA * rnA * rnA + iB * rnB * rnB;
// Compute normal impulse
float impulse = K > 0.0f ? -C / K : 0.0f;
Vector2 P = impulse * normal;
cA -= mA * P;
aA -= iA * MathUtils.Cross(rA, P);
cB += mB * P;
aB += iB * MathUtils.Cross(rB, P);
}
_positions[indexA].c = cA;
_positions[indexA].a = aA;
_positions[indexB].c = cB;
_positions[indexB].a = aB;
}
// We can't expect minSpeparation >= -b2_linearSlop because we don't
// push the separation above -b2_linearSlop.
return minSeparation >= -3.0f * Settings.LinearSlop;
}
// Sequential position solver for position constraints.
public bool SolveTOIPositionConstraints(int toiIndexA, int toiIndexB)
{
float minSeparation = 0.0f;
for (int i = 0; i < _count; ++i)
{
ContactPositionConstraint pc = _positionConstraints[i];
int indexA = pc.indexA;
int indexB = pc.indexB;
Vector2 localCenterA = pc.localCenterA;
Vector2 localCenterB = pc.localCenterB;
int pointCount = pc.pointCount;
float mA = 0.0f;
float iA = 0.0f;
if (indexA == toiIndexA || indexA == toiIndexB)
{
mA = pc.invMassA;
iA = pc.invIA;
}
float mB = 0.0f;
float iB = 0.0f;
if (indexB == toiIndexA || indexB == toiIndexB)
{
mB = pc.invMassB;
iB = pc.invIB;
}
Vector2 cA = _positions[indexA].c;
float aA = _positions[indexA].a;
Vector2 cB = _positions[indexB].c;
float aB = _positions[indexB].a;
// Solve normal constraints
for (int j = 0; j < pointCount; ++j)
{
Transform xfA = new Transform();
Transform xfB = new Transform();
xfA.q.Set(aA);
xfB.q.Set(aB);
xfA.p = cA - MathUtils.Mul(xfA.q, localCenterA);
xfB.p = cB - MathUtils.Mul(xfB.q, localCenterB);
Vector2 normal;
Vector2 point;
float separation;
PositionSolverManifold.Initialize(pc, xfA, xfB, j, out normal, out point, out separation);
Vector2 rA = point - cA;
Vector2 rB = point - cB;
// Track max constraint error.
minSeparation = Math.Min(minSeparation, separation);
// Prevent large corrections and allow slop.
float C = MathUtils.Clamp(Settings.Baumgarte * (separation + Settings.LinearSlop), -Settings.MaxLinearCorrection, 0.0f);
// Compute the effective mass.
float rnA = MathUtils.Cross(rA, normal);
float rnB = MathUtils.Cross(rB, normal);
float K = mA + mB + iA * rnA * rnA + iB * rnB * rnB;
// Compute normal impulse
float impulse = K > 0.0f ? -C / K : 0.0f;
Vector2 P = impulse * normal;
cA -= mA * P;
aA -= iA * MathUtils.Cross(rA, P);
cB += mB * P;
aB += iB * MathUtils.Cross(rB, P);
}
_positions[indexA].c = cA;
_positions[indexA].a = aA;
_positions[indexB].c = cB;
_positions[indexB].a = aB;
}
// We can't expect minSpeparation >= -b2_linearSlop because we don't
// push the separation above -b2_linearSlop.
return minSeparation >= -1.5f * Settings.LinearSlop;
}
public static class WorldManifold
{
/// <summary>
/// Evaluate the manifold with supplied transforms. This assumes
/// modest motion from the original state. This does not change the
/// point count, impulses, etc. The radii must come from the Shapes
/// that generated the manifold.
/// </summary>
/// <param name="manifold">The manifold.</param>
/// <param name="xfA">The transform for A.</param>
/// <param name="radiusA">The radius for A.</param>
/// <param name="xfB">The transform for B.</param>
/// <param name="radiusB">The radius for B.</param>
/// <param name="normal">World vector pointing from A to B</param>
/// <param name="points">Torld contact point (point of intersection).</param>
public static void Initialize(ref Manifold manifold, ref Transform xfA, float radiusA, ref Transform xfB, float radiusB, out Vector2 normal, out FixedArray2<Vector2> points)
{
normal = Vector2.Zero;
points = new FixedArray2<Vector2>();
if (manifold.PointCount == 0)
{
return;
}
switch (manifold.Type)
{
case ManifoldType.Circles:
{
normal = new Vector2(1.0f, 0.0f);
Vector2 pointA = MathUtils.Mul(ref xfA, manifold.LocalPoint);
Vector2 pointB = MathUtils.Mul(ref xfB, manifold.Points[0].LocalPoint);
if (Vector2.DistanceSquared(pointA, pointB) > Settings.Epsilon * Settings.Epsilon)
{
normal = pointB - pointA;
normal.Normalize();
}
Vector2 cA = pointA + radiusA * normal;
Vector2 cB = pointB - radiusB * normal;
points[0] = 0.5f * (cA + cB);
}
break;
case ManifoldType.FaceA:
{
normal = MathUtils.Mul(xfA.q, manifold.LocalNormal);
Vector2 planePoint = MathUtils.Mul(ref xfA, manifold.LocalPoint);
for (int i = 0; i < manifold.PointCount; ++i)
{
Vector2 clipPoint = MathUtils.Mul(ref xfB, manifold.Points[i].LocalPoint);
Vector2 cA = clipPoint + (radiusA - Vector2.Dot(clipPoint - planePoint, normal)) * normal;
Vector2 cB = clipPoint - radiusB * normal;
points[i] = 0.5f * (cA + cB);
}
}
break;
case ManifoldType.FaceB:
{
normal = MathUtils.Mul(xfB.q, manifold.LocalNormal);
Vector2 planePoint = MathUtils.Mul(ref xfB, manifold.LocalPoint);
for (int i = 0; i < manifold.PointCount; ++i)
{
Vector2 clipPoint = MathUtils.Mul(ref xfA, manifold.Points[i].LocalPoint);
Vector2 cB = clipPoint + (radiusB - Vector2.Dot(clipPoint - planePoint, normal)) * normal;
Vector2 cA = clipPoint - radiusA * normal;
points[i] = 0.5f * (cA + cB);
}
// Ensure normal points from A to B.
normal = -normal;
}
break;
}
}
}
private static class PositionSolverManifold
{
public static void Initialize(ContactPositionConstraint pc, Transform xfA, Transform xfB, int index, out Vector2 normal, out Vector2 point, out float separation)
{
Debug.Assert(pc.pointCount > 0);
switch (pc.type)
{
case ManifoldType.Circles:
{
Vector2 pointA = MathUtils.Mul(ref xfA, pc.localPoint);
Vector2 pointB = MathUtils.Mul(ref xfB, pc.localPoints[0]);
normal = pointB - pointA;
normal.Normalize();
point = 0.5f * (pointA + pointB);
separation = Vector2.Dot(pointB - pointA, normal) - pc.radiusA - pc.radiusB;
}
break;
case ManifoldType.FaceA:
{
normal = MathUtils.Mul(xfA.q, pc.localNormal);
Vector2 planePoint = MathUtils.Mul(ref xfA, pc.localPoint);
Vector2 clipPoint = MathUtils.Mul(ref xfB, pc.localPoints[index]);
separation = Vector2.Dot(clipPoint - planePoint, normal) - pc.radiusA - pc.radiusB;
point = clipPoint;
}
break;
case ManifoldType.FaceB:
{
normal = MathUtils.Mul(xfB.q, pc.localNormal);
Vector2 planePoint = MathUtils.Mul(ref xfB, pc.localPoint);
Vector2 clipPoint = MathUtils.Mul(ref xfA, pc.localPoints[index]);
separation = Vector2.Dot(clipPoint - planePoint, normal) - pc.radiusA - pc.radiusB;
point = clipPoint;
// Ensure normal points from A to B
normal = -normal;
}
break;
default:
normal = Vector2.Zero;
point = Vector2.Zero;
separation = 0;
break;
}
}
}
}
}